The MMX technology supports both saturating and wraparound modes. In wraparound mode, results that overflow or underflow are truncated and only the lower (least significant) bits of the result are returned. In saturation mode, results of an operation that overflow or underflow are clipped (saturated) to a data-range limit for the data type. The result of an operation that exceeds the range of a data type saturates to the maximum value of the range, while a result that is less than the range of a data type saturates to the minimum value of the range. This method of handling overflow and underflow is useful in many applications, such as color calculations.
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PADDB mm,mm/m64 |
| The PADD (Packed Add) instructions add the data elements of the source operand to the data elements of the destination register, and the result is written to the destination register. If the result exceeds the data-range limit for the data type, it wraps around. PADD support packed byte (PADDB), packed word (PADDW), and packed doubleword (PADDD) data types.
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